This invention provides improvements in the construction of fluid power cylinders enabling such a cylinder to utilize applied pressure fluid to produce a consistently reliable and accurate signal of a given distance and direction of travel of its piston and connected rod. The signal so produced may be variously utilized.
The invention also provides a new method and system for controlling the valve used for cycling pressure fluid to and from a fluid power cylinder which is economical to fabricate, more efficient and satisfactory in use and inherently more reliable than those heretofore employed. It will be described herein in this context, but only by way of illustration and not by way of limitation.
There have, in the past, been fluid power cylinder installations incorporating stroke signalling devices such as reed type switches and special signalling valves. These, however, have not been totally dependable as to their function. It has been found that they are adversely affected by any change in cylinder speed or the back pressure which may exist in the cylinder system in which they are embodied. Such problems are eliminated in the use of embodiments of the present invention.
The invention embodiments afford even greater benefits. Since applied pressure fluid per se may be used to produce signals, component and maintenance requirements are minimized as far as controls are concerned.